The present invention relates to improvements in electronic weighing systems of the type wherein plural strain-gaged transducers sense the weight of containers, such as hoppers or tanks, and produce related electrical output signals which can be electronically translated into displays of content weight or weight changes or into automatic control of filling, batching, blending, or the like. In one particular aspect, batch weighing-system accuracy and the mountings of associated weight-responsive transducers are improved by unique combinations wherein rugged adjustable clevis-jointed expansion units are distinctively aligned and swivelled to couple all loading vertically through sensing cells notwithstanding environmentally-induced distortions which tend to develop errors.
As is well known in the art, various forms of transducer devices, or load cells, equipped with electrical strain gages may be used to characterize weights supported by a platform or container. Such cells generally perform best when they experience loadings closely aligned with a predetermined measurement axis, and all such loadings should be substantially vertical and unshunted by other mounting structure if measurement accuracy is to be maintained. For the latter purposes, it has been proposed that a weighed tank be supported on a number of shaped legs which are themselves directly gaged to represent the vertical forces, and that the legs be terminated in ball feet which may act as bearings (U.S. Pat. No. 2,597,751--Ruge). The need to avoid by-passing effects of stays, guides, check plates and the like, if measurements are to be precise, has further been taken into account in U.S. Pat. No. 3,439,761--Laimins, where transducer-supports of a parallelogram type were described as promoting wholly vertical platform deflections. Although a load cell may be made inherently highly immune to side, eccentric and angular loadings (U.S. Pat. No. 3,037,178--Pien), one should nevertheless provide that such unwanted forces will not exceed prudent limits and that optimum performance will be favored by application of the weight-responsive forces along a preferred cell axis under all expected conditions of use. U.S. Pat. No. 3,565,196--Laimins discusses the use of such cells with a weighing platform, and makes it clear that auxiliary adjustments and isolations from non-vertical and spurious loadings can be important to precision weighing even with such transducers. Automatic display and control in response to load-cell weighing are well known and may vary with the applications; U.S. Pat. No. 3,708,026--Senour, provides one example of advanced concepts associated with such electronic weighing systems.
Particular difficulty is experienced when the supported object is large and its weight relatively great and there are extremes of environmental conditions, such as widely-different seasonal temperatures. In those cases, the cells can be exposed to serious disturbing forces, and any mechanisms designed to relieve such forces must not only be sensitive but must themselves be strong and reliable; further, they should not add unreasonably to related costs of manufacture and installation of the weighing system.